Classifiers are commonly used as equipment for processing coal and mineral ore to separate smaller, fully processed particles from larger, insufficiently processed clumps or chunks. The typical classifier comprises a static outer cage made up of vertical bars or vanes arranged and anchored in a cylindrical pattern with spaces between the bars to permit air flow. A dynamic cage is mounted concentrically within the static cage for rotation about a vertical axis at the center of the structure. An air stream flows through the cages and ore is fed in from the top.
Because of the heavy and abrasive nature of the material being processed by the classifier, the vertical bars of both the static and dynamic cages are subject to a high degree of wear, particularly near the lower ends. As a result, it is common to require periodic reconstruction of at least the static classifier cage. This is a difficult and laborious job requiring disassembly of the upper classifier structure including the motor that rotates the interior cage and the support structure for the motor. Thereafter, the long heavy bars must be lifted vertically upwardly for removal purposes. If they are to be inverted and reused, their length and weight is such as to make the inversion a difficult step. Thereafter, the inverted bars are lowered back into position and reinstalled. The down time required to invert and reinstall all of the bars is substantial and results in an expensive loss of production.